This invention relates to an enclosure for use while sorting materials having a low level of radioactivity.
Waste having low levels of radioactivity is created at nuclear power plants and similar facilities. Typically, the waste comprises paper, fabrics, boots, clothing, tools and other items which can normally be expected to be used in the laboratories, offices, workshops and the like of a nuclear facility. The waste is collected in containers such as plastic bags to facilitate its handling. Prior to its disposal the waste is taken from the bags and passed through a series of inspections during which it is inspected for beta particle and gamma ray emissions.
To the extent that radioactive emissions above predetermined levels are detected, the waste is disposed of as hazardous by being buried at controlled disposal sites. Usually radiation in excess of two milliroentgens per hour indicates that a majority of the contents of a particular container are so highly contaminated that further sorting is usually not warranted.
Waste which exhibits radiation which is less than two milliroentgens per hour is subjected to closer inspection in an attempt to remove its nonradioactive components so that they can be reused where appropriate or treated as ordinary non-hazardous refuse. This reduces the volume of material that must be buried at controlled sites and provides an opportunity to recover valuable items.
An aspect of inspecting waste relates to an inspection for low level beta particle emission. This is because a failure to detect and remove articles that are low level beta particle emitters could result in injury of persons who are exposed to the radiation over a long period of time.
In order to minimize the radiation hazard to persons who are using the enclosure of the present invention, the waste is given a preliminary examination so that items exhibiting relatively high levels of radioactivity, i.e., over two milliroentgens per hour are removed. Further means can be provided for subsequent examination of articles even if only very low levels of radiation are detected in order to assure that all hazardous articles are removed.
A process for the preliminary examination of radioactive waste of which the method and apparatus disclosed herein can be a part is disclosed in co-pending patent application Ser. No. 648,780 entitled METHOD FOR SORTING RADIOACTIVE WASTE which was filed by Alfred N. Johnson and Anthony J. Prisco on Sept. 10, 1984.
The apparatus disclosed herein is operative to provide a safe environment for technicians as they manually sort materials having a low level of radioactivity. This is accomplished by providing a negative atmosphere in the enclosure so that radioactive particles cannot drift from the enclosure into the ambient air. Further, risk of hazard is reduced by virtue of the preliminary inspection of materials which is described in detail in the above mentioned co-pending patent application.